One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,5)(4,6)(7,8)(9,10)(11,17)(12,15)(13,16)(14,19)(18,23)(20,22)(21,24)(25,26)(27,35)(28,33)(29,39)(30,34)(31,37)(32,36)(38,40) involution — undirected(1,3)(2,5)(4,7)(6,8)(9,11)(10,14)(12,18)(13,19)(15,21)(16,17)(20,24)(22,23)(27,36)(31,40)(32,35)(37,38) involution — undirected(3,7)(5,8)(9,12,13,20)(10,15,16,22)(11,18,19,24)(14,21,17,23)(25,27)(26,31)(28,37)(29,38)(30,36)(32,33)(34,40)(35,39)(2,6)(3,7)(11,19)(14,17)(18,24)(21,23)(25,27)(26,32)(28,38)(29,37)(30,36)(31,33)(34,35)(39,40) involution — undirected(3,7)(5,8)(10,16)(14,17)(15,22)(21,23)(25,28,30,29)(26,33,34,39)(27,37,36,38)(31,32,40,35)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.